Origin of median sacral artery with fourth pair of lumbar artery - an alert for spine surgeons and interventionalists: A case report and mini literature review.

The median sacral artery (MSA) is the single unpaired dorsal branch of the abdominal aorta. The present case describes the relatively unusual origin of the median sacral artery in common with the fourth pair of lumbar arteries via a common trunk in a 74-year-old males' cadaver. Unusual common trunk is prone for iatrogenic injury in surgeries of the lumbar and pelvic region. Owing to the deep seated nature of MSA close to the periosteum of lumbar vertebrae and sacrum, detection of accidental rupture of MSA and ligation thereof becomes a difficult task. MSA is also increasingly being utilized for intra-arterial embolization of pelvic tumours. The proximal portion of the common origin may at times undergo cone shaped dilatation which is referred to as infundibulum or infundibular dilatation and can also transform into aneurysm later. Knowledge of this variation is imperative for spine and pelvic surgeons to avoid unwanted complications.

Iliac vein variation in the sacral promontory on three-dimensional computed tomography angiography: a prospective observational study before laparoscopic sacrocolpopexy.

INTRODUCTION AND HYPOTHESIS: Venous injury may occur during exposure of the anterior longitudinal ligament at the anterior sacral promontory (SP). We aimed to quantitatively measure the extent of the vascular window (VW) in front of the SP in patients with internal iliac vein (IIV) variations using preoperative three-dimensional computed tomography angiography (3DCTA). We hypothesized that patients with IIV variations would have a narrow VW. METHODS: This prospective observational study included patients scheduled for laparoscopic sacrocolpopexy (LSC) between July 2022 and April 2023 who underwent preoperative 3DCTA. The primary endpoint was the VW measurement in the standard and variant IIV groups using 3DCTA before LSC. The secondary endpoint was the difference between the two IIV groups adjusted for age, body mass index, hypertension, and diabetes using an analysis of covariance (ANCOVA) model. Multiple regression analysis was performed to analyze the effect of factors on the distance from the SP to great vascular bifurcations. RESULTS: There were 20 cases of IIV variation (20.2%). VW was 28.8 ± 12.4 mm in the variant group and 39.6 ± 12.6 mm in the standard group (p = 0.001). In the ANCOVA model, IIV variations affected VW (coefficient, -11.8; 95% confidence interval [CI], -18.4 to -5.08, p < 0.001). Multivariate analysis revealed that the aorta-SP distance decreased with age (coefficient, -0.44; 95% CI, -0.77 to -0.11, p = 0.009). CONCLUSIONS: One in five women has a vascular variant at the SP that restricts the "safe" zone of fixation to < 3 cm.

The Shunt Point of the Sacral Dural Arteriovenous Fistula: A Case Report and Literature Review.

BACKGROUND: The occurrence of sacral dural arteriovenous fistula (dAVF) is rare. The detailed vascular architecture of sacral dAVF, including 3-dimensional (3D) angiographic images with operative findings, has not been evaluated compared with that of the thoracic and lumbar levels. We report a case of sacral dAVF with 3D angiographic examination and operative findings, with a literature review. CASE DESCRIPTION: A 60-year-old man presented with progressive urinary incontinence and gait disturbance. A sacral dAVF was detected at the S1-2 level. The shunt point was at the medial side of the line between the intermediate sacral crest and the most medial point of the L5 pedicle circle at the anterior posterior view of the angiography; we defined this type as the medial type. After embolization, latent inflow arteries were visualized ipsilaterally and contralaterally. During surgery, because of dAVF recurrence, a vascular tangle was found on the dura. The surgical interruption of the draining vein improved the patient's symptoms. From the literature review, 92% of cases had medial-type shunt point. It is possible for sacral dAVF to have multiple inflow arteries originating ipsilaterally or bilaterally, and a venous pouch. CONCLUSIONS: The shunt point of sacral dAVF tended to be located medially, not in the sacral foramen. Sacral dAVF has unique angioarchitecture. The differentiation of dAVF from epidural arteriovenous fistula may not be easy in some cases of sacral lesions. Therefore, further studies with a larger number of patients focused on the detailed vascular architecture are needed.

Republished: Transradial approach in the treatment of a sacral dural arteriovenous fistula: a technical note.

Sacral dural arteriovenous fistulas (SDAVFs) are rare, constituting no more than 10% of all spinal dural fistulas. They are most commonly fed by the lateral sacral artery (LSA), a branch of the internal iliac artery (IIA). Catheterization of this vessel requires either a crossover at the aortic bifurcation in cases of right femoral access or retrograde catheterization from the ipsilateral common femoral artery. We present the case of a 79-year-old man with tethered cord syndrome and a symptomatic SDAVF fed by two feeders from the left LSA. Spinal diagnostic angiography was made exceptionally challenging by an aorto-bi-iliac endograft, and selective catheterization of the left IIA was not possible. The patient could not undergo surgery due to multiple comorbidities, therefore embolization was considered the best approach. The procedure was carried out through a transradial access (TRA) with Onyx and n-butyl cyanoacrylate. The SDAVF was successfully treated and the patient made a full neurological recovery.

Transradial approach in the treatment of a sacral dural arteriovenous fistula: a technical note.

Sacral dural arteriovenous fistulas (SDAVFs) are rare, constituting no more than 10% of all spinal dural fistulas. They are most commonly fed by the lateral sacral artery (LSA), a branch of the internal iliac artery (IIA). Catheterization of this vessel requires either a crossover at the aortic bifurcation in cases of right femoral access or retrograde catheterization from the ipsilateral common femoral artery. We present the case of a 79-year-old man with tethered cord syndrome and a symptomatic SDAVF fed by two feeders from the left LSA. Spinal diagnostic angiography was made exceptionally challenging by an aorto-bi-iliac endograft, and selective catheterization of the left IIA was not possible. The patient could not undergo surgery due to multiple comorbidities, therefore embolization was considered the best approach. The procedure was carried out through a transradial access (TRA) with Onyx and n-butyl cyanoacrylate. The SDAVF was successfully treated and the patient made a full neurological recovery.

Anterior robotic approach in en-bloc sacrectomy: a preliminary experience.

En-bloc sacrectomy is a highly demanding surgical procedure necessary to obtain wide margin in sacral tumor. The double approach, anterior and posterior approach, is usually preferred for tumors extending proximally to S3 level where iliac internal vessels are at a higher risk for damage during posterior surgery. It can be justified also in selected cases to decrease the risk of posterior approach as in local recurrence or in patients who already underwent laparotomy. Our intent was to apply robotic-assisted techniques for performing anterior preparatory approach for sacrectomy surgery. Between December 2010 and December 2014, three cases of sacrectomies were performed in a previous robotic-assisted preparatory approach to separate the rectum from the tumor. Dissections were successfully performed in all cases close to the pelvic floor. The surgeon was able to position a Gore-Tex spacer between the anterior tumor surface and the rectum in all cases. The anterior dissections were performed with a perfect control of bleeding. No complications related to the anterior approach were reported. Robot-assisted surgery can be considered a valid and minimally invasive technique which allows a safe anterior dissection of the pelvic structures dividing tumors from surrounding tissues. It allows to place a spacer to protect organs during posterior sacral resection performed on the same day or at a later time. Further experiences are advocated to evaluate its efficiency in sacral tumors of greater size.

Presentation and outcomes of patients with thoracic and lumbosacral spinal epidural arteriovenous fistulas: a systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Thoracolumbar and sacral spinal epidural arteriovenous fistulas (SEDAVFs) are an increasingly recognized form of spinal vascular malformation. The purpose of this study was to perform a systematic review of the demographics, clinical presentation and treatment results of thoracolumbar SEDAVFs. MATERIALS AND METHODS: Pubmed, Scopus and Web of Science databases were searched from January 2000 to January 2018 for articles on treatment of SEDAVFs. Pooled data of individual patients were analyzed for demographic and clinical features of SEDAVFs as well as treatment outcomes. RESULTS: There were 125 patients from 11 studies included. Mean age was 63.5 years. There was a male sex predilection (69.6%). Sensory symptoms including pain or numbness were the most frequently presenting symptoms. Fistula location was the lumbosacral spine in 79.2% and the thoracic spine in 20.8%. Involvement of intradural venous drainage was more common than extradural venous drainage only (89.6% vs 10.4%). Of the 123 treated patients, endovascular therapy was performed in 67.5% of patients, microsurgery in 23.6%, and combined treatment in 8.9%. The overall complete obliteration rate was 83.5% and did not differ between groups. Clinical symptoms improved in 70.7% of patients, were stable in 25%, and worsened in 1.7% with no difference between treatment modalities. CONCLUSIONS: Thoracic and lumbosacral SEDAVFs often present with symptoms secondary to congestive myelopathy or compressive symptoms. Both endovascular and microsurgical treatments were associated with high obliteration rates and good clinical outcomes.

Laparoscopic Division of Median Sacral Artery and Dissection of Types III and IV Sacrococcygeal Teratomas to Decrease Intraoperative Hemorrhagic Complications: Case Series and Review of the Literature.

INTRODUCTION: Sacrococcygeal teratoma (SCT) is the most common teratoma presenting at birth. Life-threatening bleeding is a major complication during tumor excision in children. In this study we demonstrate our technique for laparoscopic division of median sacral artery (MSA) during dissection of SCT in 2 pediatric patients as a safe technique to minimize risk of hemorrhage. METHODS: Two female infants diagnosed with types III and IV SCTs underwent preoperative evaluation in the postnatal period. The first patient was an 18-month-old girl who presented with metastatic type IV teratoma, resected after neoadjuvant therapy, and the second patient was a 6-day-old girl with prenatal diagnosis of cystic type III teratoma. Using laparoscopy in both patients, the presacral space was reached by opening the peritoneal reflection with blunt dissection and the MSA was identified. Then it was carefully isolated and divided with 3 or 5 mm sealing device. The pelvic components of the tumors were partially dissected using laparoscopy. The first patient's tumor resection was completed using a posterior sagittal approach and the second patient required a standard Chevron incision. Along with the description of our technique, a review of the current literature for the management of SCT and MSA was performed. RESULTS: Both patients underwent successful laparoscopic division of the MSA and resection of the SCTs without complications. CONCLUSION: Laparoscopic MSA division before SCT excision offers a safe approach that can reduce the risk of hemorrhage during surgery.

Fetal median sacral artery anatomy study by micro-CT imaging.

PURPOSE: The median sacral artery (MSA) is the termination of the dorsal aorta, which undergoes a complex regression and remodeling process during embryo and fetal development. The MSA contributes to the pelvic vascularization and may be injured during pelvic surgery. The embryological steps of MSA development, anastomosis formation and anatomical variations are linked, but not fully understood. METHODS: The pelvic vascularization and more precisely the MSA of a human fetus at 22 weeks of gestation (GW) were studied using micro-CT imaging. Image treatment included arterial segmentations and 3D visualization. RESULTS: At 22 GW, the MSA was a well-developed straight artery in front of the sacrum and was longer than the abdominal aorta. Anastomoses between the MSA and the internal pudendal arteries and the superior rectal artery were detected. No evidence was found for the existence of a coccygeal glomus with arteriovenous anastomosis. CONCLUSIONS: Micro-CT imaging and 3D visualization helped us understand the MSA central role in pelvic vascularization through the ilio-aortic anastomotic system. It is essential to know this anastomotic network to treat pathological conditions, such as sacrococcygeal teratomas and parasitic ischiopagus twins (for instance, fetus in fetu and twin-reversed arterial perfusion sequence).

Awareness of middle sacral artery pathway: A cadaveric study of the presacral area.

PURPOSE: To assess the anatomic path of the middle sacral artery (MSA) at the presacral area and its relationship to the spinal midline during an axial lumbar interbody fusion (AxiaLif) approach. METHODS: Fifty human cadavers (25 males, 25 females) were used in this study. A transabdominal approach was used to expose the anterior aspect of the L5/S1 intervertebral disc and the presacral space. We measured the size and distance from the spinal midline at the following positions: (a) middle of the L5/S1 disc level, (b) 1 cm below the sacral promontory (SP), and (c) 2 cm below the SP. Each parameter was measured three times by two observers, and the mean value analyzed. RESULTS: The MSA was present and originated from the left common iliac artery in all cadavers with a mean width of 2.14 mm. The position of the MSA in relation to the midline was most commonly on the left side (LS, 56%) followed by the right side (RS, 34%) and midline (ML, 10%). In the LS group, the distance from the midline is relatively constant in the three measured positions with a mean value of (a) 1.78 mm (range, 0-8.17 mm), (b) 2.08 mm (range, 0-7.10 mm), and (c) 2.06 mm (range, 0-9.76 mm). In the RS group, the distance from the midline increased from cephalad to caudad, with a mean value of (a) 1.44 mm (range, 0-9.64 mm), (b) 2.19 mm (range, 0-9.95 mm), and (c) 2.92 mm (range, 0-10.03 mm). CONCLUSIONS: Our study found the presacral anatomic path of the MSA was most commonly at the left of midline. In addition, the right-sided MSA variant had increasing distance from the midline along its anatomic path from cephalad to caudad. Our findings suggest an AxiaLif approach at the left of midline may place the MSA at greatest risk.

The middle rectal artery arising from the lateral sacral artery.

A middle rectal artery arising from the lateral sacral artery (MRAls) in the right pelvis of a 99-year-old male was observed. Although variations of the origin of the middle rectal artery have been reported on many occasions, there are few descriptions of the trajectory in the literature. In our case, the MRAls branched from the lateral sacral artery on the sacral surface close to the third sacral sympathetic ganglion and immediately penetrated the third sacral splanchnic nerve and the parasympathetic pelvic splanchnic nerve from the ventral ramus of the forth sacral nerve. The MRAls entered in the lateral wall of the rectal ampulla without giving off a prostatic branch. Preservation of the pelvic autonomic nerves are crucial in rectal cancer excision to preserve the autonomic functions. The close topography of the MRAls to the origin of the fine autonomic nerves should be noted.

Efficacy of rectus muscle fragment welding in the control of presacral venous bleeding.

BACKGROUND: The incidence of presacral venous bleeding during rectal resection is low, but this complication can be severe and even lethal. Occasionally, the traditional methods - such as pelvic gauze packing and the use of metallic thumbtacks - are not effective. When combined with their complications and difficulties, these failures have resulted in numerous creative procedures with which to control this complication. In 1994, the indirect electrocoagulation method, which is performed via a fragment of the rectus abdominis muscle of the abdomen, was introduced to control presacral venous bleeding. METHODS: From January 2002 to December 2015, five of 872 patients with rectal cancer and one patient with rectal metastasis of gastric cancer developed presacral venous bleeding, and this technique was used in every case. RESULTS: Haemostasis was permanent in all cases. There were no complications such as infection or rebleeding. CONCLUSION: In our experience, indirect electrocoagulation via a fragment of the rectus abdominis muscle of the abdomen is a rapid, easily executed and effective method for controlling presacral venous bleeding during rectal resection.

Sacral dural arteriovenous fistulas: a diagnostic and therapeutic challenge - single-centre experience of 13 cases and review of the literature.

BACKGROUND: Sacral dural arteriovenous fistulas (DAVFs) are rare vascular abnormalities of the spine characterised by slowly progressive symptoms that can mimic different myelopathy disorders. OBJECT: To report our single Institution experience with sacral DAVFs. METHODS: We retrospectively reviewed the clinical records of patients admitted from 1 January 2006 to 31 December 2016 with a diagnosis of sacral DAVFs, treated by endovascular embolisation or surgical clipping. Clinical presentation, imaging characteristics, treatment results and follow-up were analysed. RESULTS: We identify 13 patients with sacral DAVFs supplied by lateral sacral arteries. Clinical presentation was characterised by different degrees of motor weakness and sphincter disturbances. In all patients, spinal MRI showed spinal cord hyperintensities with enhancement and prominent perimedullary vessels. Selective internal iliac angiography was mandatory to identify the exact location of the fistula. A complete embolisation was achieved in eight patients performing a single endovascular embolisation and in three patients performing a single surgical disconnection: two patients required combined procedures. Follow-up imaging showed a complete resolution of the spinal cord hyperintensities in 81% of patients and a reduction of the intramedullary enhancement in 91%. Gait improvement was observed in 73% of patients, while remaining stable in 27%. Sphincter disturbances improved in 36% of patients and remained stable in 64%. CONCLUSION: Awareness of sacral location of DAVFs is critical because standard spinal angiography will not identify sacral supplies, unless internal iliac arteries are properly examined. In our experience, the endovascular treatment show results comparable to surgery when the fistula point is correctly disconnected.

A Case of Common Peroneal Nerve Palsy Associated with Internal Iliac Artery Embolization by Using N-butyl-2-cyanoacrylate (NBCA).

A 64-year-old man was scheduled to undergo endovascular aneurysm repair for an abdominal aortic aneurysm (AAA). Since preoperative computed tomography showed an AAA with common iliac artery and internal iliac artery (IIA) aneurysms, IIA embolization was scheduled. Embolization using a coil was supposed to be performed; however, the lateral sacral artery could not be selected. For this reason, IIA embolization using N-butyl-2-cyanoacrylate (NBCA) was undertaken. During embolization, the median sacral artery was unexpectedly embolized through the lateral sacral artery. The patient complained of drop foot just after embolization; he was diagnosed with iatrogenic common peroneal nerve palsy. We have learned that sciatic nerve palsy can occur in cases of embolization with a liquid NBCA-Lipiodol mixture to the lateral or sacral median artery.

Anatomical differences in patients with lumbosacral transitional vertebrae and implications for minimally invasive spine surgery.

OBJECTIVE The objective of this study was to investigate the neurovascular and anatomical differences in patients with lumbosacral transitional vertebrae (LSTV) and the associated risk of neurovascular injury in minimally invasive spine surgery. METHODS The authors performed a retrospective study of CT and MR images of the lumbar spine obtained at their institution between 2010 and 2014. The following characteristics were evaluated: level of the iliac crest in relation to the L4-5 disc space, union level of the iliac veins and arteries in relation to the L4-5 disc space, distribution of the iliac veins and inferior vena cava according to the different Moro zones (A, I, II, III, IV, P) at the L4-5 disc space, and the location of the psoas muscle at the L4-5 disc space. The findings were compared with findings on images obtained in 28 age- and sex-matched patients without LSTV who underwent imaging studies during the same time period. RESULTS Twenty-eight patients (12 male, 16 female) with LSTV and the required imaging studies were identified; 28 age- and sex-matched patients who had undergone CT and MRI studies of the thoracic and lumbar spine imaging but did not have LSTV were selected for comparison (control group). The mean ages of the patients in the LSTV group and the control group were 52 and 49 years, respectively. The iliac crest was located at a mean distance of 12 mm above the L4-5 disc space in the LSTV group and 4 mm below the L4-5 disc space in the controls. The iliac vein union was located at a mean distance of 8 mm above the L4-5 disc space in the LSTV group and 2.7 mm below the L4-5 disc space in the controls. The iliac artery bifurcation was located at a mean distance of 23 mm above the L4-5 disc space in the LSTV group and 11 mm below the L4-5 disc space in controls. In patients with LSTV, the distribution of iliac vein locations was as follows: Zone A, 7.1%; Zone I only, 78.6%; Zone I encroaching into Zone II, 7.1%; and Zone II only, 7.1%. In the control group, the distribution was as follows: Zone A only, 17.9%; Zone A encroaching into Zone I, 75%; and Zone I only, 7.1%. There were no iliac vessels in Zone II in the control group. The psoas muscle was found to be rising away laterally and anteriorly from the vertebral body more often in patients with LSTV, resulting in the iliac veins being found in the "safe zone" only 14% of the time, greatly increasing the risk of vascular injury. CONCLUSIONS In patients with LSTV, the iliac crest is more likely to be above the L4-5 disc space, which increases the technical challenges of a lateral approach. The location of the psoas muscle rising away laterally and ventrally in patients with LSTV compared with controls and with the union of the iliac veins occurring more often above the L4-5 disc space increases the risk for iatrogenic vascular injury at the L4-5 level in this patient population.

Characterization of the median sacral artery course at the sacral promontory using contrast-enhanced computed tomography.

INTRODUCTION AND HYPOTHESIS: Laparoscopic sacral colpopexy (SC) is increasingly utilized in the surgical management of apical prolapse. It involves attachment of a synthetic mesh to the sacral promontory and to the prolapsed vaginal walls. The median sacral artery (MSA) runs close to the site of mesh attachment and is therefore prone to intraoperative injury, which may lead to profound hemorrhaging. The aim of this study was to determine the location of the MSA at the level of the sacral promontory with regard to adjacent visible anatomical landmarks. Surgeons may use this information to reduce the risk for presacral bleeding. METHODS: Sixty consecutive contrast-enhanced pelvic computed tomography scans were revised, and the location of the MSA at the level of the sacral promontory was determined in relation to the ureters, iliac arteries, sacral midline, and aortic bifurcation. RESULTS: The MSA runs 0.2 ± 3.9 mm left to the midline of the sacral promontory and 48.0 ± 15.4 mm caudal to the aortic bifurcation. The ureters, internal and external iliac arteries on the right were significantly closer to the MSA than on the left (30.0 ± 7.1 vs 35.2 ± 8.8 mm, p = 0.001; 21.5 ± 6.8 vs 30.3 ± 8.4 mm, p < 0.0001; 32.8 ± 10.2 vs 41.9 ± 14.5 mm, p = 0.005 respectively). CONCLUSIONS: The MSA, which runs left to the midline of the sacral promontory, and its location can be determined intraoperatively in relation to adjacent visible anatomical structures. The iliac vessels and ureter on the right are significantly closer to the MSA than those on the left. This information may help surgeons performing SC to avoid MSA injury, thus reducing operative morbidity.

Median sacral artery injury following a bone marrow biopsy successfully treated with selective trans-arterial embolization: a case report.

BACKGROUND: Iatrogenic arterial injury during bone marrow biopsy is an extremely rare complication. We present unreported complication of median sacral artery injury that was managed successfully with endovascular treatment. CASE PRESENTATION: A 22-year-old Caucasian man known to have end-stage renal disease secondary to Senior-Loken syndrome presented with anemia. He underwent an investigation with bone marrow biopsy that was complicated by hypotension and a further significant drop in his hemoglobin level. Cross-sectional imaging with computed tomography demonstrated a large abdominopelvic retroperitoneal hematoma and active bleeding of the median sacral artery. A successful lifesaving endovascular trans-arterial embolization was performed on an emergency basis and our patient was discharged in a stable condition a few days later. CONCLUSION: Iatrogenic arterial injury after a bone marrow biopsy is extremely rare. To the best of our knowledge, a median sacral artery injury has not been previously reported. Endovascular trans-arterial embolization is a safe, effective, and minimally invasive therapeutic option.

Critical Anatomy Relative to the Sacral Suture: A Postoperative Imaging Study After Robotic Sacrocolpopexy.

OBJECTIVE: This study aimed to characterize pertinent anatomy relative to the sacral suture placed at time of robotic sacrocolpopexy using postoperative computed tomography and magnetic resonance imaging. METHODS: A vascular clip was placed at the base of the sacral suture at the time of robotic sacrocolpopexy. Six weeks postoperatively, subjects returned for a computed tomography scan and magnetic resonance imaging. RESULTS: Ten subjects completed the study. The middle sacral artery and vein coursed midline or to the left of midline in all the subjects. The left common iliac vein was an average of 26 mm from the sacral suture. To the right of the suture, the right common iliac artery was 18 mm away. Following the right common iliac artery to its bifurcation, the right internal iliac was on average 10 mm from the suture. The bifurcations of the inferior vena cava and the aorta were 33 mm and 54 mm further cephalad, respectively.The right ureter, on average, was 18 mm from the suture. The thickness of the anterior longitudinal ligament was 2 mm.The mean angle of descent of the sacrum was 70 degrees. Lastly, we found that 70% of the time, a vertebral body was directly below the suture; the disc was noted in 30%. CONCLUSIONS: We describe critical anatomy surrounding the sacral suture placed during robotic sacrocolpopexy. Proximity of both vascular and urologic structures within 10 to 18 mm, as well as anterior ligament thickness of only 2 mm highlights the importance of adequate exposure, careful dissection, and surgeon expertise.

The surgical neurovascular anatomy relating to partial and complete sacral and sacroiliac resections: a cadaveric, anatomic study.

PURPOSE: Pelvic and sacral surgeries are considered technically difficult due to the complex multidimensional anatomy and the presence of significant neurovascular structures. Knowledge of the key neurovascular anatomy is essential for safe and effective execution of partial and complete sacral resections. The goal of this anatomic, cadaveric study is to describe the pertinent neurovascular anatomy during these procedures. METHODS: Three embalmed human cadaveric specimens were used. Sacrectomies and sacroiliac joint resections were simulated and the structures at risk were identified. Both anterior and posterior approaches were evaluated. RESULTS: During sacroiliac joint resection, L5 nerve roots are at high risk for iatrogenic injury; the vasculatures at greatest risk are the common iliac vessels and internal iliac vessels with L5-S1 and S1-S2 high sacrectomies. Minor bleeding risk is associated with S2-S3 osteotomy because of the potential to damage superior gluteal vessels. S3-S4 osteotomy presents a low risk of bleeding. Adjacent nerve roots proximal to the resection level are at high risk during higher sacrectomies. CONCLUSIONS: Several sacrectomy techniques are available and selection often depends on the specific case and surgeon preference; nevertheless, anatomic knowledge is extremely important. Considering the highly variable anatomic relations of the vascular bundles, a preoperative evaluation with CT or MRI with vascular reconstruction may be helpful to decrease bleeding risk by preemptively binding the internal iliac vessels in cases where higher tumors are present. To decrease the risk of damaging nerve roots, it is recommended to perform the resection as close to the involved foramina as possible.

Awareness of the median sacral artery during lumbosacral spinal surgery: an anatomic cadaveric study of its relationship to the lumbosacral spine.

PURPOSE: The purpose was to investigate the median sacral artery (MSA) anatomical pathway in terms of its relationship to the lumbosacral spine. METHODS: The posterior wall and lumbosacral spine of 54 adult embalmed cadavers were dissected. The MSA emerging point was identified. The distance from its emerging point to the lateral border of the vertebral body was measured bilaterally. The pathway of the MSA from the emerging point to the sacral promontory was described together with the MSA length. All outcomes were independently measured by two observers. Statistics on obtained data were calculated. RESULTS: Most of the MSA emerging points were at the L5 vertebral body (94.4 %). The emerging point from the right and left lateral border of the L5 vertebral body was 3.31 ± 0.54 cm and 2.39 ± 0.51 cm, respectively. The MSA then lay along the middle one-third of the anterior surface of the lumbosacral junction. The mean length between the emerging point and the sacral promontory was 2.73 ± 0.97 cm. CONCLUSIONS: The MSA anatomy is important for prevention of intra-operative bleeding. For anterior lumbosacral surgery, the MSA should be identified and controlled before proceeding with the spinal surgery. For posterior bicortical sacral screw placement, the screw tip should be fluoroscopically checked to avoid inserting the screw tip into the mid sacral promontory. By first approaching the anterior sacral promontory, the surgeon will find the MSA within the middle one-third zone, and 2.47-2.99 cm cephalad to this, the iliac vessels. Knowledge of the MSA helps the surgeon to operate more safely.